How do compressors work audio

Shooting for a lower ratio on your compressors can bring back some punch into your mix. Soft knee means the compression will be applied gradually as the signal approaches the threshold. Hard knee means the compression will be applied quickly as soon as the audio surpasses the threshold. So this will turn down the overall volume of that channel. I like to bypass the plugin on and off to make sure the channel is still well balanced in the mix.

Fast attack and release times can sometimes cause low frequencies to distort. Low frequencies have long waves so the fast attack causes the gain reduction to begin working within one cycle of the wave causing it to clip. The problem is, sometimes you need the fast attack time to attenuate the transient of the audio. This means the compressor begins the gain reduction a few milliseconds before the transient, allowing the low frequencies to pass through undistorted.

Click below to find out more. Download the fully functional trials of our plugins to help you get better sounding mixes FREE for 15 days. Close search. Just added to your cart. As with all of the signal processing tools available to us, understanding what each of the controls — both generically and in the context of a specific device — is essential to being able to use that tool effectively.

In terms of compressors and limiters, it is vital to understand how each control changes the way the compressor treats the programme material if you want to use this very powerful form of signal processing effectively. The appropriate compressor settings are entirely dependent on the level and dynamics of the material being processed and the artistic effect you are trying to achieve by compressing it.

This is why the library settings provided in a lot of digital mixers and intended for various generic sound sources are inherently pointless! Most compressors include a meter to show the amount of gain reduction being applied at any moment, and comparing this with the levels of the input and output signals can be very instructive in understanding what each control does. Ultimately, though, this is an audible effect and so only your ears are able to judge the effectiveness, and appropriateness, of your chosen settings.

As with all signal processing, it is usually better to under-process than over-process — if the material sounds compressed, you are applying too much gain reduction. There have been lots of articles about both basic and advanced compression techniques in Sound On Sound over the years, which should provide you which plenty more information about this much-talked-about but often misunderstood subject.

I suggest you do a search for Technique articles via the search page of the Sound On Sound web site www. Previous article Next article. New forum posts Re: New synth challenge -- scoring a silent film! However, if we turned the ratio up to very high , the expander would output signals at levels of 8 dB, 16 dB, and 32 dB below the threshold.

These signals are now much further apart and much closer to being inaudible. Eventually, as the ratio increases, any signal will be greatly attenuated, and all signal that passes through the gate will have to cross this floor level.

Every gate will have at least three parameters: threshold, attack time, and release time. These all function the same as in compressors and expanders. Some gates will also have a hold parameter, causing the gate to remain open for a period of time in ms after the signal has dropped below the threshold and before the release phase begins.

Some gates will also offer the ability to have the gate close at a different level than the threshold, which is only used for opening the gate. This parameter is often called the close or return level. And just like the fact that some limiters have an adjustable ceiling, some gates will have an adjustable floor level. Now that we know a gate is essentially an expander with a high ratio, take a look at our expansion output level equation again:.

As the ratio increases, that total fraction will become larger and larger. As expected, as the ratio increases, the output level for a signal that falls below the threshold will become quieter and quieter.

Eventually, the signal will not be able to pass if it is below the threshold—a gate. This can be on a vocal to eliminate breaths, or can be used as an expander to isolate louder signals in a recording e.

Gates are equally useful in a studio recording or live sound context. They can also be used in a similarly creative way as the expander example above. However, a gate would cause that static sample to pump harder and therefore have a more difficult time blending with the drums. Therefore, you may just want to use an expander for that. Additionally, the level balance between elements over the course of a track is super important for mixing.

As a result, dynamics processors like compressors, limiters, expanders, and gates are invaluable tools for any producer or mix engineer. Make sure to try the dynamics processing shown in this article with a free trial of Music Production Suite Pro. Streaming loudness normalization and data compression can be a bit of a mystery. In this article, we investigate how Spotify performs these processes.

Want to know which mistakes to avoid when mixing? Learn the difference between the four most popular audio formats—. Get top stories of the week and special discount offers right in your inbox.

You can unsubscribe at any time. Get the highest quality sound every time. Music Production Suite Pro. Try for Free. Explore the future of mastering:. Ozone 9. Learn More. Let your vocals cut through the mix:.

Nectar 3 Plus. Never Miss an Article! Limiters Expanders Gates. Want to try this out yourself? What do compressors do? Threshold The threshold is the level at which dynamics processing begins. Ratio How much compression that occurs once the signal rises above the threshold is controlled by the ratio. The following figure illustrates a threshold of various ratios.

Knee The knee affects how a compressor behaves with signals that are very near the threshold. Here is an example starting with a hard knee, moving to a soft knee. Attack and Release Times Remember, we said that the threshold activates the compressor, not compression in general. Compression of a series of tones showing the effect of attack and release time. Why use a compressor? Transient Shaping You can also use compressors to shape transients in sounds like drums.

Parallel and Sidechain Compression There are two other techniques worth mentioning where compression is concerned. What do limiters do? Limiter parameters Every limiter will have at least one parameter: gain. Why use a limiter? What do expanders do? Expander parameters The parameters found in an expander are and function mostly the same as those in a compressor.

Downward expansion does not require makeup gain, as the quiet parts will simply be quieter. Why use an expander? With Reverb. Without Reverb After Expansion. Dry Drums. The is perfect for vocals, bass, guitar and more. It's also a popular choice for bringing out excitement in room mics.

VCA Fast and punchy VCA compressors run the gamut — from the Rolls-Royce compression of the SSL G Bus or E series used on the mix bus and instrument groups, to the hot-rod attitude of the legendary dbx , which can give a snare drum or electric guitar unrelenting character.

Here are a few suggestions to get you up and running with compression. These are certainly not rules, but hopefully these techniques will help you feel more confident when using this extremely powerful, but easily misused recording tool.

Have fun, and experiment. Always listen carefully while adding compression. Compression can negatively affect the timbre of an instrument. Fast compression on instruments with wide vibrato will demonstrate this effect. Try starting with a moderate to medium ratio of between and Set your attack time to a medium-fast setting and your release time to a medium setting.

Then set your output gain to compensate for the 5 dB attenuation. Finally, speed up your attack time gradually until it gets noticeable and then back it off slightly. Experiment with using dramatic compression as an effect. In many types of popular music, there will be a bass line with a fairly constant signal level.

You can avoid this by using a multiband compressor such as the Precision Multiband Compressor , which splits the signal into multiple frequency ranges, allowing you to compress them separately. Learn essential functions of popular tube and solid-state compressor varieties, and creative uses for your productions.